Could that sexy underwire bra cause breast cancer? What about that frozen yogurt you just ordered? Or hormone therapy? And how would you know if you had the disease until it was too late anyway? Don't some studies show that examining your breasts and getting mammograms are useless?

Amid all the rumors and controversies surrounding breast cancer these days, what causes it, how to diagnose and treat it, it's hard to know what to think. Or do. One thing we can tell you is that being able to separate fact from fiction could make a difference between life and death.

No risk factor either alone or in combination with others means you'll definitely get breast cancer. There are various factors that may increase your risk of developing the disease. Some of these appear to increase your risk only slightly. They include smoking, drinking (more than 5 alcoholic drinks per week year after year), getting your first menstrual period before age 12, continuing to have periods after age 55, and not having your first full-term pregnancy until after age 30. If you have a number of these, the increase in risk can start to be more meaningful.

That said, even an inherited genetic abnormality in your family doesn't necessarily mean you're going to get breast cancer. Abnormalities in the so-called breast cancer genes BRCA1 and BRCA2 are very strong risk indicators. But 20 to 60 percent of women with these inherited abnormalities will not develop breast cancer.

Myth 2 — If there is no breast cancer in your family, then you're not at risk for the disease.

Every woman is at risk for breast cancer. So are some men! For any individual woman, an inherited abnormality is the strongest risk factor, but only about 10 percent of all cases of breast cancer are due to inherited abnormalities. About 85 percent of women who develop the disease don't have a family history. That's why it's important for all women to get screened regularly.

Myth 3— Breast cancer is passed only from your mother, not your father.

We now know that breast cancer genes can be inherited from your dad's side of the family. So ask relatives about cases on both sides and in both men and women. About 2,000 cases of male breast cancer are diagnosed in the US each year. In fact, male breast cancer is most closely associated with a BRCA2 abnormality. So if there's a man in the family who's had breast cancer, be sure to tell your doctor.

Myth 4 — No matter what your risk factors are, you really don't have to worry about breast cancer until you're through menopause.

The odds of getting the disease do increase as you age. But breast cancer can occur at any age. That's why all women need to be vigilant. Though experts recommend yearly mammograms starting at age 40, your doctor may suggest that you start even earlier if you have a family history of breast cancer at a young age.

Mammography isn't the ideal screening test for women younger than 40 because it can't "see through" their dense breast tissue. So your doctor may also recommend ultrasound or magnetic resonance imaging (MRI). You may be able to enroll in a study of MRI for breast cancer detection for women at increased risk.

These are two Internet rumors that never seem to quit. It's not true that wearing a bra, especially underwire bras, traps toxins by limiting lymph and blood flow in your breasts, increasing risk. There's also no proof for the claims that antiperspirants and deodorants cause cancer by keeping the body from sweating out the cancer-causing substances that build up in the breasts, or because they contain harmful chemicals that are absorbed through the skin.

Myth 6 — If you have small breasts, you're much less likely to get breast cancer.

Size doesn't matter. Anyone with breasts can get it.

Myth 7 — Research shows that using hormone therapy (HT) even for a short period of time, causes breast cancer.

Many women were understandably concerned when a major study found that HT combining estrogen and progestin increased risks of invasive breast cancer slightly. Another study also showed that a combination of therapy boosts breast cancer risk somewhat, however, it was able to offer some reassurance: This risk appeared to return to normal within a year or so after women stopped using the therapy. This seems to be the case for women who've been on HT for just months and those who've used it for more than 5 years.

One more thing: It's important to note that no studies have found a boost in breast cancer risk for women using estrogen-only therapy. This type of therapy is prescribed solely for women who have had hysterectomies, because estrogen taken alone can cause cancer in the lining of the uterus (endometrial cancer).

Myth 8 — A number of studies have found that women who live in countries where diets tend to be lower in fat have a lower risk of breast cancer. But the majority of studies focusing on women in the US haven't found a solid link between dietary fat consumption and breast cancer risk. Why are these finding contradictory? It may be that women in other countries are at lower risk for other reasons: They exercise more, eat less, weigh less, smoke less, or have a different genetic profile or environmental interaction that makes them less susceptible. One thing we do know: Postmenopausal obesity is a risk factor that does put you at risk for breast and other cancers, so it pays to maintain a healthy weight.

As for dairy products, the study results are mixed. But Harvard's Nurses' Health Study, a large-scale study of 120,000 women, recently found that premenopausal women who ate a lot of dairy products, especially low-fat and fat-free ones, ran a lower risk of breast cancer. The study found no link between dairy product consumption and breast cancer risk in women who are past menopause.

Myth 9 — Mammograms can prevent breast cancer.

A 2003 Harris survey of more than 500 women found that about 30 percent thought mammograms could prevent breast cancer. The truth: While mammograms can detect breast cancer, they can't prevent it.

Myth 10 — Some studies actually show mammograms are worthless.

Two studies, including a review study done by Danish scientists, did suggest that getting a regular mammogram didn't lower a women's risk of dying of breast cancer. But several other studies, including one done by the US preventive Services Task Force, totally disagree. You can maximize the benefit of mammography screening by seeking out the best facilities and staff in your area. Look for the radiology center that handles the most breast cancer cases in the region. Go to a radiologist who specializes in reading mammograms, and ask, "How many mammograms do you read each year?" More tends to be better. A study in the Journal of the National Cancer Institute found that radiologists who read more than 300 mammograms a month were more accurate.